Light source system employing two light emitting devices and related projection system employing two spatial light modulators

ABSTRACT

A light source system comprises: a light-emitting device for emitting a first light and a second light in sequence; a beam splitting system with which the first light is divided into one beam in a first range of wavelength and the other beam in a second range of wavelength, respectively emitted along a first optical path and a second optical path, and also with which at least a part of the second light is emitted along the first optical path; a first spatial light modulator for modulating the beam emitted from the beam splitting system along the first optical path; a second spatial light modulator for modulating the beam emitted from the beam splitting system along the second optical path. The light source system has the advantages of high light-emitting efficiency and low cost. A projection system comprising the aforementioned light source system is also provided.

BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates to lighting and display technologies, and inparticular, it relates to a light source system and related projectionsystem.

Description of the Related Art

In conventional single-plate digital micromirror device (DMD) system,multiple primary lights sequentially and alternatingly enters the DMD tobe modulated. The modulated single-color images rapidly switch on thescreen, so that a color image is perceived by the viewer due to mixingof the sequential single-color images by the effect of persistence ofvision of the human eyes. In conventional technologies, typically red(R), green (G) and blue (B) primary color lights are used formodulation. A commonly used method of generating a three primary colorlight sequence is to use an excitation light to excite differentsegments of a color wheel sequentially to generate different colorlights sequentially. In such a structure, the excitation light mayemploy a blue LED (light emitting diode) or blue laser. The color wheelhas three segments, one of which being a light transmitting segmentwhich transmits the blue light, while the other two carry green and redphosphors, respectively, to absorb the excitation light and generategreen and red converted lights, respectively.

However, in such a light source device that uses phosphors, red phosphoris a bottleneck that limits that working life and light emissionefficiency of the light source device. The wavelength conversionefficiency of red phosphor tends to be relatively low; the energy notconverted to red light becomes heat, which quickly raises thetemperature of the phosphor, which in turn adversely affects its lightemitting efficiency and life, causing a vicious cycle.

SUMMARY OF THE INVENTION

The main technical problem solved by this invention is to provide alight source system that has high light emitting efficiency andrelatively low cost.

An embodiment of the present invention provides a light source system,which includes:

a light generating device which sequentially generates a first light anda second light;

a light division system which divides the first light from the lightgenerating device into a light in a first wavelength range and a lightin a second wavelength range and outputs them along a first light pathand a second light path, respectively, and which outputs at least a partof the second light from the light generating device along the firstlight path;

a first spatial light modulator, which modulates the light outputtedfrom the first light path of the light division system; and

a second spatial light modulator, which modulates at least a part of thelight outputted from the second light path of the light division system.

Another embodiment of the present invention provides a projection systemthat includes the above light source system.

Compared to conventional technologies, the light source system accordingto embodiments of the present invention has the following advantages:

It divides the first light into the light in the first wavelength rangeand the light in the second wavelength range, and these two lights andthe at least part of the second light are outputted sequentially; thus,in certain time intervals only two lights are output, and in certainother time intervals only one light is output, so that two spatial lightmodulators can be used to modulate the three lights. Further, the lightsource system can use a wavelength conversion material having arelatively high wavelength conversion efficiency to generate a convertedlight and then divide that converted light into two other colors, wherethe two other color lights would otherwise have required two wavelengthconversion material having relatively low wavelength conversionefficiency; this increases the efficiency of the light source system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the spectrum of a yellow light generated by a yellowphosphor.

FIG. 2 schematically illustrates a light source system according to anembodiment of the present invention.

FIG. 3A illustrates an example of the time sequence of the color lightoutputted by the wavelength conversion layer 203 in FIG. 2.

FIGS. 3B and 3C respectively illustrate examples of the modulation timesequences of the DMD 211 and DMD 213 in FIG. 2, respectively, fordifferent color lights.

FIG. 4 illustrates another example of the modulation time sequence ofthe DMD 213 for red light.

FIG. 5 schematically illustrates a light source system according toanother embodiment of the present invention.

FIG. 6 schematically illustrates a light source system according toanother embodiment of the present invention.

FIG. 7 schematically illustrates a light source system according toanother embodiment of the present invention.

FIG. 8 is a plan view of an example of the color wheel 703 in FIG. 7.

FIG. 9 is a plan view of an example of the light division device 609 inFIG. 6.

FIG. 10 schematically illustrates a light source system according toanother embodiment of the present invention.

FIG. 11 schematically illustrates a light source system according toanother embodiment of the present invention where the wavelengthconversion layer is fixedly connected to the first light divisiondevice.

FIG. 12 schematically illustrates a light source system according toanother embodiment of the present invention.

FIG. 13A illustrates an example of the time sequences of the blue andyellow color lights outputted by the wavelength conversion layer 1203 inFIG. 12.

FIGS. 13B and 13C respectively illustrate examples of the modulationtime sequences of the DMD 1211 and DMD 1213 in FIG. 12, respectively,for different color lights.

FIG. 14 schematically illustrates a light generating device of a lightsource system according to another embodiment of the present invention.

FIG. 15 schematically illustrates the structure of the light generatingdevice set in FIG. 14.

FIG. 16 schematically illustrates a light source system according toanother embodiment of the present invention.

FIG. 17A illustrates an example of the time sequence of the lightsoutputted by the light source system of FIG. 16.

FIGS. 17B and 17C respectively illustrate examples of the modulationtime sequences of the DMD 1611 and DMD 1613 in FIG. 16, respectively,for different color lights.

FIG. 18 schematically illustrates a light source system according toanother embodiment of the present invention.

FIG. 19 is a plan view of an example of the light filter in the lightsource system of FIG. 18.

FIG. 20 illustrates an example of the time sequence of the lightsoutputted by the two light sources and the modulation time sequences ofthe two DMDs in the light source system of FIG. 18.

FIG. 21 is a plan view of another example of the light filter in thelight source system of FIG. 18.

FIG. 22 schematically illustrates a light source system according toanother embodiment of the present invention.

FIG. 23 is a plan view of an example of the light filter in the lightsource system of FIG. 22.

FIG. 24 schematically illustrates a light generating device in a lightsource system according to another embodiment of the present invention.

FIG. 25 illustrates an example of the time sequence of the lightsoutputted by the three light sources and the modulation time sequencesof the two DMDs in the light source system of FIG. 24.

FIG. 26 schematically illustrates a light generating device in a lightsource system according to another embodiment of the present invention.

FIG. 27 illustrates an example of the time sequence of the lightsoutputted by the four light sources and the modulation time sequences ofthe two DMDs in the light source system of FIG. 26.

FIG. 28 schematically illustrates a light generating device in a lightsource system according to another embodiment of the present invention.

FIG. 29 is a plan view of an example of a wavelength conversion layer inthe light source system of FIG. 28.

FIG. 30 illustrates an operating sequence of the light source system ofFIG. 28.

FIG. 31 schematically illustrates a light generating device in a lightsource system according to another embodiment of the present invention.

FIG. 32 schematically illustrates the structure of a light source systemaccording to another embodiment of the present invention.

FIG. 33 schematically illustrates the structure of a light source systemaccording to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A principle of the various embodiments of the present invention includethe following: a light generating device sequentially outputs a firstlight and a second light; a light division system divides the firstlight into two lights which fall in two different wavelength ranges andtravel along two different light paths. This way, in certain timeintervals, two lights in different wavelength ranges are output to twospatial light modulators, and in certain other time intervals, at leasta part of the second light is output to one of the two spatial lightmodulators, so that the two spatial light modulators can respectivelymodulate three different lights. In the mean time, a yellow phosphor,which has a relatively high wavelength conversion efficiency, is used togenerate a yellow light which is then divided into a red light and agreen light; this avoids the use of red phosphors which has relativelylow wavelength conversion efficiency, thereby increasing the efficiencyof the light source system.

FIG. 1 illustrates an exemplary spectrum of a yellow light generated bya yellow phosphor. It can be seen that the yellow light has a relativelywide spectrum, covering the red and green spectral ranges. Thus, theyellow light can be divided into a red light and a green light. Forconvenience of description, the yellow spectrum describe below refers tosuch a yellow light that covers the red and green spectrum, which can bedivided by a light division device into a red light and a green lighttraveling in different directions.

Embodiments of the present invention are described below with referenceto the drawings.

First Embodiment

Referring to FIG. 2, which schematically illustrates a light sourcesystem according to an embodiment of the present invention. The lightsource system of this embodiment includes a light generating device 1, alight division system 2, a first spatial light modulator 211, and asecond spatial light modulator 213.

The light generating device 1 includes an excitation light source 201for generating an excitation light, a wavelength conversion layer 203,and a first drive device 205. The wavelength conversion layer 203includes a first segment and a second segment. The first segment isprovided with a first wavelength conversion material that absorbs theexcitation light and emits a first light; the second segment is a lighttransmitting segment, which transmits the excitation light as a secondlight. In this embodiment, the excitation light source 201 generates ablue excitation light. The excitation light source 201 is preferably alaser source, but can also be an LED or other solid-state light source.The first segment of the wavelength conversion layer 203 is providedwith a yellow phosphor, for absorbing the excitation light andgenerating a yellow converted light as the first light. The secondsegment is a light transmitting segment, which transmits the blue lightas the second light. The wavelength conversion layer 203 is disk shaped,and the different segments of the wavelength conversion layer aredistributed in a circumferential direction on the disk.

The first drive device 205 drives the wavelength conversion layer 203,such that the excitation light forms a light spot on the wavelengthconversion layer 203 which falls on different segments of the wavelengthconversion layer 203 along a predetermined path. The excitation lightspot sequentially illuminates the first segment and second segment, sothat the first light and second light are outputted sequentially. Inthis embodiment, the first drive device 205 is a motor that drives thewavelength conversion layer 203 to rotate.

The light division system 2 divides the first light from the lightgenerating device 1 into a light in a first wavelength range and a lightin a second wavelength range which are output along a first light pathand second light path, respectively. It also outputs at least a part ofthe second light from the light generating device 1 along the firstlight path. The first spatial light modulator 211 modulates the lightoutputted from the first light path of the light division system; thesecond spatial light modulator 213 modulates at least a part of thelight outputted from the second light path of the light division system.The light modulated by the first spatial light modulator 211 and thesecond spatial light modulator 213 are combined and outputted to theprojection area.

In this embodiment, the light division system 2 divides the yellow lightinto a green line as the light in the first wavelength range, and a redlight as the light in the second wavelength range. In the followingexamples, when the yellow first light is divided into green light andred light, the light in the first wavelength range and light in thesecond wavelength range are not necessarily green light and red light,respectively; these two wavelength ranges are relative concepts, and thelight in the first wavelength range and light in the second wavelengthrange may also the red light and green light, respectively.

The first spatial light modulator 211 modulates a light sequence of blueand green lights, and the second spatial light modulator 213 modulatesthe red light. Because the yellow phosphor has a high light conversionefficiency, and because the blue light is directly generated by a lightemitting device, using the blue light to excite the yellow phosphor togenerate the three primary colors results in a high efficiency lightsource system.

In one implementation, the light division system 2 includes acombination of total internal reflection (TIR) prisms 207 and 209. Eachof the two prisms is a rod having a triangular cross-section; the sidefaces of the first prism 207 are 207 a, 207 b and 207 c, and the sidefaces of the second prism 209 are 209 a, 209 b and 209 c. The side face207 c of the first prism 207 is joined with the side face 209 c of thesecond prism 209.

The excited light 23 outputted by the wavelength conversion layer 203enters the first prism 207 from the side face 207 b, is reflected bytotal internal reflection on the side face 207 a, passes through theside face 207 c to enter the second prism 209 from the side face 209 c,and reaches the side face 209 a. The side face 209 a is coated with afilter film which transmits red light and reflects blue and green light.The light sequence of blue and green light is reflected by the coatedsurface 209 a, then reflected by the face 209 c by total internalreflection, before passing through the face 209 b and entering the firstspatial light modulator 211 via the first light path. The modulated blueand green lights is incident on the side face 209 b and passes throughit, is reflected on the side face 209 c by total internal reflection andthen reflected by the coated surface 209 a, before passing through theside face 209 c and passing through the prism 207. The red light passesthrough the coated surface 209 a to enter the second spatial lightmodulator 213 via the second light path. The modulated red light passesthrough the second prism 209 and first prism 207 in turn, and iscombined with the modulated green light into one light beam.

Each spatial light modulator may be a DMD, or liquid crystal or othertypes of spatial light modulator. The embodiments below use DMD as anexample.

Refer to FIG. 3A, which illustrates an example of the time sequence ofthe color light outputted by the wavelength conversion layer 203 in FIG.2. In this embodiment, the first segment of the wavelength conversionlayer 203 occupies 270 degrees and the second segment occupies 90degrees. From a starting time point where the second segment of thewavelength conversion layer 203 begins to enter the input path of theexcitation light, within a period T of the rotation of the wavelengthconversion layer 203, the operation of the light source system is asfollows. In the first 0.25 T period, the wavelength conversion layer 203outputs a blue light; in the last 0.75 T period, it outputs a yellowlight. Correspondingly, in the first 0.25 T, the DMD 211 operates tomodulate the blue light, and the DMD 213 does not operate. In the last0.75 T, the DMD 211 operates to modulate the green light, and the DMD213 operates to modulate the red light. Refer to FIGS. 3B and 3C, whichrespectively illustrate the modulation time sequences of the DMD 211 andDMD 213, respectively, for different color lights. Under this operationcondition, in each period T, the red light and green light are fullyutilized, and the utilization of the light source is maximized. However,this may not be the case in actual operation, because it is possiblethat a white light formed by mixing such three primary color lights mayhave color coordinates that do not meet predetermined color coordinatesrequirements. In actual operation, the two DMDs may be used to vary thelengths of modulation times for each color to control the colorcoordinates of the resulting white light. For example, in oneimplementation, if the red light is too strong and causes the resultingwhite light to have a red tint to it, the DMD 213 may be controlled toshorten the modulation time so that in a certain time period the redlight is not output. Refer to FIG. 4, which illustrates another exampleof the operating time sequence of the DMD 213 for red light. In the FIG.4, the red light is discarded in a time interval near the end of eachtime period T. In practice, the red light may be discarded in a timeinterval near the beginning of the period T or in one or more timeintervals anywhere within the period T.

Further, the above ratios of the first segment and second segment areonly examples; the ratios can be determined by practical considerationsand are not limited to the above examples.

In this embodiment, the light generating device sequentially outputs thefirst light and the second light, and a light division system dividesthe first light into two lights of different wavelength ranges anddifferent traveling directions. This way, within certain time periodstwo lights of different wavelength ranges are outputted to two differentspatial light modulators, and within another time period at least a partof the second light is outputted to one of the tow spatial lightmodulators, so that the two spatial light modulators can modulate threedifferent lights.

In practical applications, the TR prism 209 of the light division system2 may also have its face 209 a coated with a filter film that transmitsgreen and blue light and reflects red light. In this situation, the DMD211 may be used to modulate red light and the DMD 213 may be used tomodulate green and blue lights. As another alternative, the filter filmon the face 209 a may be one that transmits green light and reflects redand blue light. In this situation, the DMD 211 may be used to modulatered and blue lights and the DMD 213 may be used to modulate green light.The filtering spectrum of the film on face 209 a may be designed basedon practical needs.

The above-described light paths of the converted light in the two TIRprisms are only examples; different TIR prisms may be used as well.

In the above embodiment, two prisms are used to both divide the yellowlight into red and green lights and combine the two modulated lightsfrom the two DMDs into a combined light. In practice, a dichroic filterplate may be used to divide the yellow light, and downstream from thetwo DMDs, a dichroic filter plate may be used to combine the modulatedlight.

Second Embodiment

Refer to FIG. 5, which schematically illustrates a light source systemaccording to another embodiment of the present invention. In thisembodiment, the light source system 500 includes a light generatingdevice 1, a light division system 2, a first spatial light modulator 511and a second spatial light modulator 513. The light generating device 1includes an excitation light source 501, a wavelength conversion layer503 and a first drive device 505.

Differences between this embodiment and the embodiment of FIG. 2include:

The light division system 2 includes a filter plate 509 and a reflector507. The filter plate 509 receives the yellow light 53 and blue light 55sequentially outputted by the wavelength conversion layer 503; ittransmits the blue light 55 and the green component 53 a of the yellowlight 53 and outputs them to the DMD 511 via a first light path, andreflects the red component 53 b of the yellow light 53 to the reflector507. The reflector 507 reflects the red light 53 b via the second lightpath to the DMD 513.

Preferably, the light source system 500 further includes a filter plate515 and reflector 517 disposed respectively on the output path of theDMD 511 and DMD 513. The reflector 517 reflects the light sequence ofblue and green lights modulated by the DMD 511 to the filter plate 515.The filter plate 515 reflects the blue and green lights from thereflector 517, and transmits the red light from the DMD 513, to combinethe output lights of the DMD 511 and DMD 513 into one beam of light. Itshould be understood that in other embodiment, the output angles of theDMD 511 and DMD 513 may be adjusted to combine these two output lightsinto one beam. Further, in some applications, it is not necessary tocombine the output lights of the DMD 511 and DMD 513 into one beam, sothe reflector 517 and filter plate 515 can be omitted.

Third Embodiment

Refer to FIG. 6, which schematically illustrates a light source systemaccording to another embodiment of the present invention. In thisembodiment, the light source system 600 includes a light generatingdevice 1, a light division system 2, a first spatial light modulator 611and a second spatial light modulator 613. The light generating device 1includes an excitation light source 601, a wavelength conversion layer603 and a first drive device 605.

Differences between this embodiment and the embodiment of FIG. 5include:

The light division system 2 includes a first light division device 609,a second drive decide 607, and a first control device (not shown in thedrawing). To increase the utilization efficiency of the output light ofthe light generating device 1, the light source system 600 additionallyincludes a light collecting lens 615 disposed on the light path betweenthe light generating device 1 and the light division system 2, forcollecting the light sequence of yellow light 63 and blue light 65 fromthe light generating device, and to relay the collected light to thefirst light division device 609. The first light division device 609 hasa disk shape which is divided into a first segment and a second segmentin the circumferential direction. The second drive device 607 drives thefirst light division device 609 so that the first and second segmentsare sequentially disposed on the output path of the light generatingdevice 1. The first control device controls the rotation of the firstdrive device 605 and the second drive device 607, so that the firstlight division device 609 and the wavelength conversion layer 603 rotatesynchronously; as a result, the first segment is located on the outputpath of the first light, i.e. the yellow light 63, and the secondsegment is located on the output path of the second light, i.e. the bluelight 65.

The first segment of the first light division device 609 transmits thegreen component of the yellow light 63 and outputs it via the secondlight path to the DMD 613, and reflects the red component of the yellowlight 63 and outputs it via the first light path to the DMD 611. Thesecond segment reflects the blue light 65 and outputs via the firstlight path to the DMD 611. Of course, in practice, alternatively, thefirst segment may reflect red and transmit green light; or, the secondsegment may transmit a part of the blue light and reflects a part of it,and the transmitted and reflected blue lights may respectively bemodulated by the DMD 611 and DMD 613, or the DMDs may modulate one ofthe two blue lights.

Fourth Embodiment

Refer to FIG. 7, which schematically illustrates a light source systemaccording to another embodiment of the present invention. In thisembodiment, the light source system 700 includes a light generatingdevice 1, a light division system 2, a first spatial light modulator 711and a second spatial light modulator 713. The light generating device 1includes an excitation light source 701, a wavelength conversion layer703B and a first drive device 705. The light division system 2 includesa first light division device 703A and a light guiding device 3.

Differences between this embodiment and the embodiment of FIG. 6include:

In this embodiment, the wavelength conversion layer 703B and the firstlight division device 703A are fixedly connected, and mounted on thecolor wheel 703. Refer to FIG. 8, which is a plan view of an example ofthe color wheel 703 in FIG. 7. The color wheel 703 are provided with twoconcentric and nested ring-shaped regions 703A and 703B, where the ring703A is the light division region, i.e., the first light divisiondevice, and the ring 703B is the wavelength conversion region, i.e. thewavelength conversion layer. The light division region 703A includes afirst segment S1 which transmits the green light and outputs it to thefirst light path and reflects the red light and outputs it to the secondlight path. The light division region 703A also includes a secondsegment S2 which transmits the blue light and outputs it to the firstlight path. The wavelength conversion region 703B includes a firstsegment W1, which carries a yellow wavelength conversion material togenerate a yellow converted light. This segment is disposed at a180-degree position from the first segment S1 of the light divisionregion 703A with respect to the ring center. The wavelength conversionregion 703B also includes a second segment W2, which is a transmissionregions that transmits the blue light. This segment is disposed at a180-degree position from the second segment S2 of the light divisionregion 703A with respect to the ring center. The first drive device 705drives the color wheel 703 to rotate, such that the first segment W1 andsecond segment W2 are sequentially disposed on the output path of thelight generating device 1.

The light guiding device 3 guides the sequence of output lights from thefirst segment W1 and second segment W2 of the wavelength conversionlayer 703B respectively to the first segment S1 and second segment S2 ofthe first light division region 703A, in the following manner.

In this embodiment, the light guiding device 3 includes a lens 707 andreflectors 709 and 715. Within a rotation period T of the color wheel703, during the first time interval t1, the excitation light 71 from theexcitation light source 701 is incident on the first segment W1 of thewavelength conversion layer 703B and a yellow converted light isgenerated; this output converted light 73 exits the side of thewavelength conversion layer 703B that faces away from the excitationlight, and is collected by the lens 707. The light is then reflected inturn by reflectors 709 and 715, and then incident on the first segmentS1 of the light division region 703A at a 45 degree incident angle. Thegreen component and red component of the yellow light are respectivelytransmitted and reflected by the first segment S1, and respectivelyoutputted to the DMD 711 along the first light path and to the DMD 713along the second light path.

During a later time interval t2, the excitation light 71 is incident onthe segment W2 and a blue light is output. This light is guided by thelight guiding device 3 to incident on the second segment S2 at a 45degree angle, transmitted through it, and then enters the DMD 711 alongthe second light path. The line connecting the light spot A formed bythe excitation light 71 on the light division region 703A and the lightspot B formed on the wavelength conversion layer 703B pass through thering center. Of course, in practice, the incident angle when the outputlight 73 enters the light division region 703A may be other than 45degrees, and can be any angle greater than 0 depending on practicalneeds.

Hence, compared to the light source system of FIG. 6, here thewavelength conversion layer and the first light division device canrotate synchronously, increasing their synchrony and eliminating theneed for a control device to control their synchronous motion, whichreduces cost and the system's size.

Fifth Embodiment

Refer to FIG. 9, which is a plan view of an example of the lightdivision device 609 in FIG. 6. Different from the light source system ofFIG. 6, in this embodiment the first light division device 609 includesthree segments. The first segment R1 transmits the red light to outputit via the first light path, and reflects green light to output it viathe second light path. The second segment R2 transmits green light tooutput it via the first light path, and reflects red light to output itvia the second light path. The third segment transmits a part of theblue light to output it via the first light path, and reflects a part ofthe blue light to output it via the second light path.

Correspondingly, the first control device controls the first lightdivision device 609, so that the first segment R1 and the second segmentR2 are located on the output path of the first light, and the thirdsegment is located on the output path of the second light. Morespecifically, during the time period T where the yellow light it output,in a first time interval t1, the first segment R1 is located on theoutput path of the yellow light, and during a later time interval t2,the second segment R2 is located on the output path of the yellow light;and when the blue light is output, the third segment R3 is located onthe output path of the blue light.

In this embodiment, within the time period when the wavelengthconversion layer 603 rotates to generate a sequence of yellow (Y) andblue (B) lights, the DMD 611 sequentially receives a light sequence ofgreen (G), red (R) and blue (B) lights, and the DMD 613 sequentiallyreceives a light sequence of R, G and B lights. Therefore, compared toother embodiments described above, in this embodiment, the two DMD caneach receive a light sequence of three primary lights, so that each DMDcan modulates an image by itself. Moreover, during any time intervals,both DMD are operating, so the DMDs can be more fully utilized.

It should be understood that in this embodiment, the wavelengthconversion layer and the first light division device may be fixedlyconnected together. Correspondingly, on the color wheel 703 of the lightsource system of FIG. 7, the first segment S1 of the light divisionregion will be further divided into a first sub-region and a secondsub-region; the first sub-region transmits the red light to output itvia the first light path to the DMD 613, and reflects green light tooutput it via the second light path to the DMD 611, and the secondsub-region transmits the green light to output it via the first lightpath to the DMD 613, and reflects red light to output it via the secondlight path to the DMD 611.

Sixth Embodiment

The light source system in FIG. 7 shows one of the ways the wavelengthconversion layer and first light division device can be fixedlyconnected. In practice, there are other ways to accomplish this. Referto FIG. 10, which schematically illustrates a light source systemaccording to another embodiment of the present invention. In thisembodiment, the light source system 1000 includes a light generatingdevice 1, a light division system 2, a first spatial light modulator1011 and a second spatial light modulator 1013. The light generatingdevice 1 includes an excitation light source 1001, a wavelengthconversion layer 1003B and a first drive device 1005. The light divisionsystem 2 includes a first light division device 1003A and a lightguiding device 3. The wavelength conversion layer 1003B and the firstlight division device 1003A are fixedly connected, and mounted on thecolor wheel 1003.

Differences between this embodiment and the embodiment of FIG. 7include:

The wavelength conversion layer 1003B has a reflective type structure,i.e., the incident light path and output path of the wavelengthconversion layer 1003B are on the same side. Also, the first segment S1of the wavelength conversion layer 1003B and the first segment W1 of thelight division device 1003A are disposed at 0 degrees from each other,and the second segment S2 and the second segment W2 of the lightdivision device 1003A are also disposed at 0 degrees from each other.I.e., each segment of the light division device and its correspondingsegment of wavelength conversion layer are disposed adjacent each other.

The light guiding device 3 includes a reflector with aperture 1007, andcollection lenses 1009 and 1015.

In this embodiment, the excitation light source 1001 is a laser sourcethat generates a blue laser light 101. The reflector 1007 is disposed onthe path of the blue laser excitation light 101. Because the etendue oflaser is relatively small, and the etendue of the converted light isrelatively large, the blue laser light 101 passes through the apertureof the reflector 1007, is collected by the lens 1009 and incident on thewavelength conversion layer 1003B. The light sequence outputted by thewavelength conversion layer 1003B is collected by the lens 1009, and amajority of it is reflected by the reflector 1007 to the light divisiondevice 1003A. The light spot formed on the light division device 1003Aand the light spot formed on the wavelength conversion layer 1003B arelocated on the same radial line of the color wheel 1003. Compared to thelight source system of FIG. 8, the optical arrangement of thisembodiment is more compact.

Seventh Embodiment

Refer to FIG. 11, which schematically illustrates a light source systemaccording to another embodiment where the wavelength conversion layer isfixedly connected to the first light division device. In thisembodiment, the light source system 1100 includes a light generatingdevice, a light division system 2, a first spatial light modulator 1111and a second spatial light modulator 1113. The light generating deviceincludes an excitation light source 1101, a wavelength conversion layer1103B and a first drive device 1105. The light division system 2includes a first light division device 1103A and a light guiding device3. The wavelength conversion layer 1103B and the first light divisiondevice 1103A are fixedly connected, and mounted on the color wheel 1103.

Differences between this embodiment and the embodiment of FIG. 10include:

The wavelength conversion layer 1003B and the light division device1003A are not two nested ring-shaped regions. Rather, a truncated cone1103C is provided at the center of the color wheel 1103, and thewavelength conversion layer 1103B is disposed on the slanted sidesurface of the truncated cone 1103C. The light division device 1103A isdisposed in a ring-shaped region of the color wheel 1103. The blueexcitation light 111 passes through the aperture of the reflector 1107and the collection lens 1109 in turn, and illuminates a segment of thewavelength conversion layer 1103B. The output light sequence from thewavelength conversion layer 1103B is collected by lens 1109, and most ofit is reflected by the reflector 1107 to a segment of the light divisiondevice 1103A that correspond to segment of the wavelength conversionlayer 1103B where the excitation light spot is.

Compared to the light source system of FIG. 10, in this embodiment,because the distance between the wavelength conversion layer 1103B andthe light division device 1103A is larger, the angle between theincident light to the reflector 1107 and the reflected light 113 from itlarger, making it easier to separate the light paths.

In the above embodiments, the second segments of the wavelengthconversion layer may carry a second wavelength conversion material,which absorbs the excitation light and convert it to the second light.For example, the excitation light source may generate a UV light, andthe first segment of the wavelength conversion layer carries a yellowphosphor to absorbs the UV light and convert it to a yellow light, andthe second segment carries a blue phosphor to absorbs the UV light andconvert it to a blue light which is the second light.

Eighth Embodiment

The structure of the light source system of this embodiment is basicallysimilar to the ones in the above-described embodiments, the differencebeing in this embodiment, the light division system further divides thesecond light into a light in a third wavelength range and a light in afourth wavelength range and outputs them respectively along the firstlight path and the second light path. The first spatial light modulatormodulates the light in the first wavelength range of the first light andthe light in the third wavelength range of the second light which areboth output along the first light path, and the second spatial lightmodulator modulates the light in the first wavelength range of the firstlight output along the second light path or additionally modulates thelight in the third wavelength range of the second light output along thesecond light path.

Using FIG. 5 as an example, the excitation light source 501 generates aUV light. The first segment of the wavelength conversion layer 503carries a yellow phosphor to absorb the UV light and generate a yellowlight. The second segment carries a blue phosphor to absorb the UV lightand generate a blue light which is the second light. Because the bluelight generated by the blue phosphor has a relatively wide spectralwidth, which covers a part of the green spectrum, the filter plate 509of the light division system is one that can divide the second lighti.e. blue light generated by the second segment into light in the thirdwavelength range and light in the fourth wavelength range, i.e. a secondblue light and a second green light. This way, the second blue light andthe second green light each has a relatively narrow spectrum andrelatively high color purity.

Correspondingly, while the blue converted light generated by the secondsegment is divided into the second blue light and the second greenlight, in the light division system shown in FIG. 2, the coating 209 aof the second prism 209 may be one that reflects the blue component ofthe blue converted light and transmits the green component, or one thattransmits the blue component and reflects the green component. In thelight division system shown in FIG. 5, the filter plate 509 may be onethat reflects the second blue light of the blue converted light andtransmits the second green light, or one that transmits the second bluelight and reflects the second green light. In the above descriptions,the same light division device of the light division system is used todivide both the first light and the second light.

In practice, two separate light division devices may be used in thelight division system to respectively divide the first light and thesecond light. Refer to FIG. 12, which schematically illustrates a lightsource system according to another embodiment of the present invention.In this embodiment, the light source system 1200 includes a lightgenerating device 1, a light division system 2, a first spatial lightmodulator 1211 and a second spatial light modulator 1213. The lightgenerating device 1 includes an excitation light source 1201, awavelength conversion layer 1203 and a first drive device 1205.

Differences between this embodiment and the embodiment of FIG. 5include:

The light division system includes filter plates 1221, 1209 and 1207,and a reflector 1219. The filter plate 1221 is disposed on the outputpath of the light sequence from the light generating device 1, toreflect the second blue light 65 b of the blue converted light andtransmit the second green light 65 a of the blue converted light and theyellow converted light 63.

The filter plate 1209 is disposed on the path of the transmitted lightof the filter plate 1221, to transmit the second green light 65 a of theblue converted light and the first green light 63 a of the yellowconverted light 63, and reflect the red light 63 b of the yellowconverted light 63. Thus, the second green light 65 a transmitted by thefilter plate 1209 and the first green light 63 a are output to the DMD1211 along the first light path. The red light 63 b reflected by thefilter plate 1209 is reflected by the filter plate 1207 to be output tothe DMD 1213 along the second light path. The second blue light 65 breflected by the filter plate 1221 is reflected by the reflector 1219and transmitted by the filter plate 1207 in turn to be output to the DMD1213 along the second light path.

When the second blue light 65 b and second green light 65 a divided fromthe blue light 65 are both used for light modulation, because morecolors are modulated by the two DMDs, the color range of the modulatedlight is increased. Correspondingly, the operation sequences of thewavelength conversion layer 1203 and DMDs 1211, 1213 are shown in FIG.13. FIG. 13A illustrates an example of the time sequences of the blueand yellow lights outputted by the wavelength conversion layer 1203.Within the rotation period T of the wavelength conversion layer 1203, inthe first time interval of 0.25 T, the wavelength conversion layer 1203outputs the blue light, and in the later time interval of 0.75 T, thewavelength conversion layer 1203 outputs the yellow light. Refer toFIGS. 13B and 13C, which respectively illustrate examples of themodulation time sequences of the DMD 1211 and DMD 1213, respectively,for different color lights. Correspondingly, in the first time intervalof 0.25 T, the DMD 1211 modulates the second green light, and the DMD1213 modulates the second blue light. In the later time interval of 0.75T, the DMD 1211 modulates the first green light, and the DMD 1213modulates the red light.

It should be understood that the second green light can also bediscarded and not modulated; i.e., when it enters the DMD 1211, the DMD1211 does not operate and does not modulate this light.

The above embodiments utilizes the wavelength differences of the lights,and achieves light division or combination using filter plates or filterfilms to transmit and reflect different color lights. Whether aparticular light in a particular light path is transmitted or reflectedby a particular filter plate is a design choice. Thus, in allembodiments of the present invention, the filter plates and filter filmsused in the various light paths are only examples, and other opticalstructures employing filter plates or filter films can be used toachieve light division and combination.

In this embodiment, the wavelength conversion layer 1203 can havemultiple segments carrying different wavelength conversion materials orlight transmitting materials; the output converted light from at leastone of the segments is divided into two lights of different wavelengthranges so that they are inputted into two spatial light modulators to bemodulated.

In this embodiment, the first and second segments can carry wavelengthconversion materials that generate other converted lights; they are notlimited to the yellow and blue phosphors described above. In addition tophosphors, the wavelength conversion materials can also be quantum dots,fluorescent dyes and other materials with wavelength conversioncapabilities.

Ninth Embodiment

Refer to FIG. 14, which schematically illustrates a light generatingdevice of a light source system according to another embodiment of thepresent invention. Different from the earlier embodiments where thelight generating device 1 generates a light sequence using a colorwheel, in this embodiment, the light generating device 1 generate alight sequence using a reflector to sequentially reflect different colorlights outputted by a LED light wheel. Compared to the first embodiment,this embodiment can reduce cost by using the reflector.

More specifically, the light generating device 1 includes a light sourceset 1401, a first reflecting device 1405, a second reflecting device1403 and a second drive device (not shown in the drawings).

The light source set 1401 includes a first light emitting device (inthis embodiment, yellow phosphor LEDs 1401 a) and a second lightemitting device (in this embodiment, blue LEDs 1401 b). A phosphor LEDrefers to an LED coated with a phosphor material, where the lightemitted by the LED excites the phosphor to generate a converted light.Commonly used yellow phosphor LEDs use a blue LED coated with a yellowphosphor, which is excited by the blue LED light to generate a yellowlight. The yellow phosphor LEDs 1401 a and blue LEDs 1401 b are arrangedin a ring shape, and the output lights of both are parallel to the axisof the ring.

The second reflecting device of this embodiment, which is a rotatingmirror 1403 with a reflecting surface 1403 a, is disposed on the outputside of the light source set 1401, between the first light emittingdevice 1401 a and the second light emitting device 1401 b.

The first reflecting device 1405 includes two reflecting elements, whichare both reflecting mirrors in this embodiment, respectively disposed onthe output paths of the first light emitting device 1401 a and thesecond light emitting device 1401 b, for reflecting the light from theselight emitting devices to the second reflecting device 1403.

The second drive device drives the second reflecting device 1403 torotate, so that the reflecting surface 1403 a is sequentially disposedon the output path of the two reflecting elements of the firstreflecting device 1405, to sequentially reflect and output the lightfrom the first and second light emitting devices.

In practice, the light source set 1401 may include multiple lightemitting device arrays, such as LED arrays in this embodiment.Correspondingly, the reflecting device 1405 may include multiplereflecting elements, respectively disposed on the output paths of themultiple light emitting device arrays.

Refer to FIG. 15, which schematically illustrates the structure of thelight generating device set 1401 in FIG. 14. Each LED of the lightgenerating device set 1401 are disposed on a disk which has the rotatingmirror 1403 at its center; they are arranged in a circumferentialdirection around the rotating mirror 1403 and arrayed in a radialdirection centered at the rotating mirror 1403. In the radial direction,each LED array emits the same color; along the circumferentialdirection, the yellow phosphor LEDs 1401 a and the blue LEDs 1401 b arealternatingly arranged.

Tenth Embodiment

Refer to FIG. 16, which schematically illustrates a light source systemaccording to another embodiment of the present invention. The lightsource system 1600 includes a light generating device 1, a lightdivision system 2, a first spatial light modulator 1611 and a secondspatial light modulator 1613.

Differences between this embodiment and the embodiment of FIG. 5include:

The light generating device 1 includes a first light emitting device, asecond light emitting device and a first control device (not shown inthe drawings), where the first light emitting device generates a firstlight and the second light emitting device generates a second light. Thefirst control device alternatingly turns on the first light emittingdevice and the second light emitting device during at least some timeintervals, to generate a light sequence of the first light and secondlight.

More specifically, the first light emitting device is a yellow LED 11 aand the second light emitting device is a blue LED 11 b to generateyellow and blue lights, respectively. The first control device controlsthe turning on and off of the different color LEDs, so that the blue LED11 b and yellow LED 11 a are alternatingly turned on to generate a lightsequence of yellow and blue lights.

In this embodiment, during certain time intervals the first controldevice can also control the yellow LED 11 a and blue LED 11 b to turn onsimultaneously. Because the blue light and the green component of theyellow light are both modulated by the DMD 1611, during the timeinterval when both the yellow LED 11 a and blue LED 11 b are turned on,the DMD 1611 modulates a combined light of the blue light and greenlight, i.e., a cyan light, while the DMD 1613 is not affected. Duringsuch time interval, because of the combination of the two lights, theDMD 1611 can modulate one more color, increasing the color range of thelight modulated by the DMD 1611.

Refer to FIG. 17A, which illustrates an example of the time sequence ofthe lights outputted by the light source system of FIG. 16. Within aperiod T, with time interval t1, the blue LED is turned on and the lightgenerating device 1 emits a blue light; with time interval t2, theyellow LED is turned on and the light generating device 1 emits a yellowlight; with time interval t3, the blue LED and yellow LED are bothturned on and the light generating device 1 emits a combined light ofthe two lights, i.e. a white light. Refer to FIGS. 17B and 17C, whichrespectively illustrate examples of the modulation time sequences of theDMD 1611 and DMD 1613, respectively, for different color lights.Correspondingly, in time interval t1, the DMD 1611 modulates the bluelight and DMD 1613 does not operate; in time interval t2, the DMD 1611modulates the green light and DMD 1613 modulates the red light; in timeinterval t3, the DMD 1611 modulates the cyan light and DMD 1613modulates the red light.

However, the two color LEDs should not always be simultaneously turnedon. This is because there are only two DMDs in the light source systemand one of them modulates blue and green lights during different timeintervals; so if the yellow LED 11 a and blue LED 11 b are always turnedon simultaneously, there will be no monochromatic images for blue andgreen and only monochromatic image for cyan.

It should be understood that if the filter plate 1609 in the lightdivision system 2 transmits red light and reflects green light, then theblue light and the red component of the yellow light will both bemodulated by DMD 1611, and the green light will be modulated by DMD1613. In such a case, during the time interval when the yellow LED 11 aand blue LED 11 b are simultaneously turned on, DMD 1611 modulates thecombined light of the blue light and red light, i.e., a purple light,while the DMD 1613 is not affected.

Compared to the other embodiments, in this embodiment, different coloredlight emitting devices can be turned on simultaneously, so that morecolors can be modulated, and the color range of the modulated light isincreased.

Eleventh Embodiment

Refer to FIG. 18, which schematically illustrates a light source systemaccording to another embodiment of the present invention. The lightsource system 1800 of this embodiment includes a light generating device1, a light division system 2, a first spatial light modulator 1811 and asecond spatial light modulator 1813.

Differences between this embodiment and the embodiment of FIG. 16include:

The light division system 2 includes a filter device 1805, a seconddrive device 1806 for driving the filter device to move, and a firstcontrol device (not shown in the drawings). The filter device 1805includes a first segment, a second segment and a third segment. Thefirst segment transmits a light in a first wavelength range in the firstlight and outputs it to the first light path, and reflects a light in asecond wavelength range and outputs it to the second light path. Thesecond segment reflects the light in the first wavelength range in thefirst light and outputs it to the second light path, and transmits thelight in the second wavelength range and outputs it to the first lightpath. The third segment transmits a part of the second light and outputsit to the first light path, and reflects a part of the second light andoutputs it to the second light path. The first control device controlsthe second drive device 1806, so that at least a part of the firstsegment and at least a part of the second segment are sequentiallydisposed on the output path of the first light, and at least a part ofthe third segment is disposed on the output path of the second light.

For example, refer to FIG. 19, which is a plan view of an example of thefilter device in the light source system of FIG. 18. The filter device1805 is disk shaped, and the various segments are distributed in acircumferential direction on the plate. The first segment 1805A of thefilter device 1805 transmits a part of the blue light and reflects apart of the blue light; the second segment 1805B transmits green lightand reflects red light; and the third segment 1805C reflects green lightand transmits red light. The second drive device 1806 is a motor, whichdrives the filter device 1805 to rotate, so that the various segmentsare sequentially disposed on the output path of the light generatingdevice 1.

Refer to FIG. 20, which illustrates an example of the time sequence ofthe lights outputted by the two light sources and the modulation timesequences of the two DMDs in the light source system of FIG. 18. Withina modulation period T, in the first time interval t1, the first segment1805A of the filter device 1805 is disposed on the output path of thelight sequence, the blue light source 1801 is turned on and the yellowlight source 1802 is turned off, and both DMDs modulate the blue light.In the next time interval t2, the second segment 1805B of the filterdevice 1805 is disposed on the output path of the light sequence, theyellow light source 1802 is turned on and the blue light source 1801 isturned off, and DMD 1811 modulates the green light and DMD 1813modulates the red light. In the next time interval t3, the third segment1805C of the filter device 1805 is disposed on the output path of thelight sequence, the yellow light source 1802 is turned on and the bluelight source 1801 is turned off, and DMD 1811 modulates the red lightand DMD 1813 modulates the green light. This way, the two DMDs canrespectively modulate the three primary colors of the light sequence.

Twelfth Embodiment

Refer to FIG. 21, which is a plan view of another example of the lightfilter in the light source system of FIG. 18.

In this embodiment, the filter device 1805 additionally includes afourth segment, which reflects blue light and transmits yellow light.Also, different from the light source system shown in FIG. 18, the firstsegment 1805A transmits blue light and reflects yellow light; when thefirst segment 1805A and the fourth segment 1805D are disposed on theoutput path of the light sequence, the blue light source 1801 and theyellow light source 1802 are both turned on. Correspondingly, within amodulation time period T, when the first segment, second segment, thirdsegment and fourth segment of the filter device 1805 are sequentiallydisposed on the output path of the light sequence, the DMD 1811sequentially modulates the blue light, green light, red light and yellowlight, and the DMD 1813 sequentially modulates the yellow light, redlight, green light and blue light. In this embodiment, because themodulated light includes a yellow light, the brightness of the lightsource system is increased.

In the light source system shown in FIG. 18, a blue light source and ayellow light source are employed and turned on in time intervalscorresponding to different segments of the filter device, to provide atleast three light sequences for the two DMDs, where the light from theblue light source is divided into two blue light beams for the two DMDs.In practice, two separate blue light sources may also be used to providetwo separate blue light beams to be modulated by the two DMDs, as shownbelow.

Thirteenth Embodiment

Refer to FIG. 22, which schematically illustrates a light source systemaccording to another embodiment of the present invention. In thisembodiment the light source system 2200 includes a light generatingdevice, a light division system, a first spatial light modulator 2211and a second spatial light modulator 2213. The light generating deviceincludes a first light emitting device 2201A, a second light emittingdevice 2202, a third light emitting device 2201B and a first controldevice (now shown in the drawings). The light division system includes afilter device 2205, a second drive device 2206, and filter plates 2203and 2204.

Differences between this embodiment and the embodiment of FIG. 18include:

The light generating device additionally includes the third lightemitting device, which generates a fourth light during at least a partof the time interval when the second light is generated. In thisembodiment, the third light emitting device is a blue light source2201B. The filter device 2205 of the light division system includes twosegments, which are the second segment and third segment in the filterdevice 1805 of the light source system shown in FIG. 18. Refer to FIG.23, which is a plan view of an example of the light filter in the lightsource system of FIG. 22. The filter device 2205 includes a firstsegment 2205A (i.e. the second segment of the filter device 1805), whichtransmits green light and reflects red light, and a second segment 2205B(i.e. the third segment of the filter device 1805), which transmits redlight and reflects green light.

The yellow light from the yellow light source 2202 (i.e. the firstlight) is incident on the filter device 2205 at an angle; the lightreflected by the filter device 2205 is transmitted through the filterplate 2204 to be output along a first light path to DMD 2211; and thelight transmitted by the filter device 2205 is transmitted through thefilter plate 2203 to be output along a second light path to DMD 2213.The light emitted by the blue light source 2201A (i.e. the second light)is reflected by the filter plate 2204 to be output along the first lightpath to DMD 2211. The light emitted by the blue light source 2201B (i.e.the fourth light) is reflected by the filter plate 2203 to be outputalong the second light path to DMD 2213.

Within a modulation period T, in the first time interval t1, the firstcontrol device turns the yellow light source 2202 off, and turns theblue light sources 2201A and 2201B on; DMD 2211 and 2213 both modulatethe blue light. In the later time interval t2, the first control deviceturns the yellow light source 2202 on, and turns the blue light sources2201A and 2201B off; at least parts of the first segment 2203A andsecond segment 2203B are sequentially disposed on the output path of theyellow light. The DMD 2211 modulates the red light and green lightsequentially output along the first light path, and DMD 2213 modulatesthe green light and red light sequentially output along the second lightpath.

In this embodiment, the intensity of the two blue lights modulated bythe two DMDs may be controlled depending on practical requirements.Further, the output time durations of the two blue lights blue may bemade different, for example, one of the blue light sources may be turnedon only during a part of the time interval when the other blue lightsource is turned on; the specific length of the on time for the bluelight sources may depend on the amount of blue light required by the twoDMD. Similarly, to adjust the amounts of the green light and red lightbeing modulated, the on times of the yellow light source when the firstsegment 2203A and second segment 2203B are respectively disposed on theoutput path of the yellow light (i.e. the first light) may becontrolled. It should be understood that one of the blue light sourcesmay be replaced by other colored light emitting devices such as cyanlight emitting devices; the corresponding one of the DMDs will thenmodulate the light sequence of cyan, red and green lights.

It should be understood that, in this embodiment, the filter plates 2203and 2204 of the light division system are not mandatory; they can beomitted by changing the optical structure of the light source system.For example, the various segments of the filter device 2205 can be madeto also transmit the second light and the fourth light (which are bothblue in this embodiment), and the light sources 2201A and 2201B can bemoved to locations on the two sides of the filter device 2205, so thatthe output light of the light source 2201A is transmitted through thefilter device 2205 and directly enters DMD 2211, and the output light ofthe light source 2201B is transmitted through the filter device 2205 anddirectly enters DMD 2213.

Fourteenth Embodiment

Refer to FIG. 24, which schematically illustrates a light generatingdevice in a light source system according to another embodiment of thepresent invention. In this embodiment the light source system 2400includes a light generating device, a light division system, a firstspatial light modulator 2411 and a second spatial light modulator 2413.

The light generating device sequentially outputs a first light, a secondlight and a third light. More specifically, the light generating deviceincludes a yellow light source 2402A, a blue light source 2401 and ayellow light source 2402B, which respectively generates yellow light22A, blue light 11 and yellow light 22B, i.e., first, second and thirdlights. The light generating device additionally includes a firstcontrol device 2403 for controlling the three light sources such thatthe light generating device sequentially outputs the yellow light 22A,blue light 11 and yellow light 22B.

The light division system divides the second light from the lightgenerating device into a first sub-light and a second sub-light whichare respectively output along a first light path and a second lightpath, and divides the third light from the light generating device intoa light in a fifth wavelength range and a light in a sixth wavelengthrange which are respectively output along the first light path and thesecond light path. More specifically, the light division system includesfilter plate 2404 and 2405. The transmission spectrum of the filterplate 2405 is one that transmits the green component of the yellowlight, i.e. the light in the first wavelength range within the firstlight and the light in the fifth wavelength range within the thirdlight, and reflects red light, i.e. the light in the second wavelengthrange within the first light and the light in the sixth wavelength rangewithin the third light; it also transmits a part of the blue light andreflects a part of the blue light, i.e. the first sub-light and a secondsub-light respectively. The filter plate 2404 transmits blue light andreflects yellow light. The light generated by the blue light source 2401and yellow light source 2402A are incident onto the filter plate 2404from its two sides; they are respectively transmitted and reflected bythe filter plate 2404 to incident on one side of the filter plate 2405along the same path. The light from the yellow light source 2402B isincident on the filter plate 2405 on another side. The light reflectedby the filter plate 2405 is output to DMD 2411 along the first lightpath and the light transmitted by the filter plate 2405 is output to DMD2413 along the second light path.

The first spatial light modulator DMD 2411 modulates the light in thefirst wavelength range, the first sub-light and light in the fifthwavelength range which are output from the light division system alongthe first light path. The second spatial light modulator DMD 2413modulates the light in the second wavelength range, the second sub-lightand light in the sixth wavelength range which are output from the lightdivision system along the second light path.

Refer to FIG. 25, which illustrates an example of the time sequence ofthe lights outputted by the three light sources and the modulation timesequences of the two DMDs in the light source system of FIG. 24. Withina modulation time period T, during the first time interval t1, the bluelight source 2401 is turned on, and the two yellow light sources areturned off; both DMDs modulate the blue light. During the next timeinterval t2, the yellow light source 2402B is turned on, and the othertwo light sources are turned off; DMD 2411 modulates the green light,and DMD 2413 modulates the red lights. During the next time interval t3,the yellow light source 2402A is turned on, and the other two lightsources are turned off; DMD 2411 modulates the red light, and DMD 2413modulates the green lights. This way, the two DMDs can each modulate alight sequence of the three primary colors.

In this embodiment, the modulation time period T can further include atime interval t4, during which all three light sources are turned on;the two DMDs both modulate a combination light of the blue light andyellow light, i.e., a white light. This way, the brightness of the lightsource system can be increased. In this embodiment, the relative lengthsof the time intervals t1, t2, t3 and t4 can be adjusted based on thepractical needs of different colored lights.

Compared to other embodiments described earlier, in this embodiment, thebrightness of the two yellow light sources can be controlled toadjustment the brightness of the red and green light modulated by thetwo DMDs; this also eliminates the need for a second drive device fordriving the filter device. Meanwhile, because the turning on of thelight sources does not need to be synchronized with the rotation of thefilter device, it makes it easier to control the sequential turning onof the different light sources, and makes it easier to adjust the amountof different color lights modulated by the DMDs.

It should be understood that, in this embodiment, one of the yellowlight sources can be replaced by a light emitting device of a thirdcolor. Correspondingly, the transmission spectrum of the filter plate2405 can be made to transmit light of one wavelength range in the thirdcolor light and reflect light of another wavelength range in the thirdcolor light.

In this embodiment, the light generating device can alternatively use anexcitation light source to excite a rotating color wheel to generatethree beams of light sequences, and the light division system can use afilter wheel that rotate in synchrony with the color wheel to achievelight division of the three beams. Such devices are already described inthe earlier embodiments; this can be achieved by combining the lightgenerating devices and light division systems of the earlier embodimentsin various ways, which will not be described in detail here.

Fifteenth Embodiment

Refer to FIG. 26, which schematically illustrates a light generatingdevice in a light source system according to another embodiment of thepresent invention. In this embodiment, the light source system 2600includes a light generating device, a light division system, a firstspatial light modulator 2611 and a second spatial light modulator 2613.The light generating device includes blue light sources 2601A and 2601B,yellow light sources 2602A and 2602B, and a first control device 2603.The light division system includes filter plates 2604 and 2605.

Differences between this embodiment and the embodiment of FIG. 24include:

In this embodiment, the light generating device additionally includesblue light source 2601B, which together with the blue light source 2601Aprovides separate blue lights to the two DMDs.

Compared to the filter plate 2405 in the light source system of FIG. 24which divides the lights from the two yellow light sources, in thisembodiment, the filter plate 2605 which divides the lights from the twoyellow light sources is one that transmits green light and reflects blueand red lights, and the blue light generated by the blue light source2601A is transmitted through the filter plate 2605 to be output to DMD2613 along the second light path. Meanwhile, the filter plate 2606 isdisposed on the output path of the reflected light of the filter plate2605, for transmitting the blue light and reflecting other lights. Thesequence of red and green lights reflected by the filter plate 2605 isreflected by the filter plate 2606 to be output to DMD 2611 along thefirst light path, and the blue light from the blue light source 2501B istransmitted through the filter plate 2606 to be output to DMD 2611 alongthe first light path.

Refer to FIG. 27, which illustrates an example of the time sequence ofthe lights outputted by the four light sources and the modulation timesequences of the two DMDs in the light source system of FIG. 26. Withina modulation time period T, during the first time interval t1, the firstcontrol device controls the two blue light sources to turn on and thetwo yellow light sources to turn off; the two DMDs both modulate bluelights. During the next time interval t2, the yellow light source 2602Bis turned on and the other three light sources are turned off; DMD 2611modulates green light, and DMD 2613 modulates red light. During the nexttime interval t3, the yellow light source 2602A is turned on and theother light sources are turned off; DMD 2611 modulates red light, andDMD 2613 modulates green light. This way, the two DMDs can each modulatea light sequence of the three primary colors.

It should be understood that one of the blue light sources canalternatively be turned on during only a part of the time interval t1,and the length of the on time can be controlled based on the amount ofblue light needed.

Preferably, the modulation time period T can further include a timeinterval t4, during which all three light sources are turned on; the twoDMDs both modulate a combination light of the blue light and yellowlight, i.e., a white light. This way, the brightness of the light sourcesystem can be increased. In this embodiment, the relative lengths of thetime intervals t1, t2, t3 and t4 can be adjusted based on the practicalneeds of different colored lights.

Compared to light source system of FIG. 24, in this embodiment, two bluelights are used, so that the intensity of the two blue lights modulatedby the two DMDs and the respective modulating time lengths can becontrolled to better suit the need of practical applications.

In the above embodiment, the transmission spectrum of each filter plate,the timing control of each light source, the modulation timing of theDMDs, and the optical path designs are not limited to the aboveexamples; those familiar with the relevant art can make adjustmentsbased on the principles described here.

Sixteenth Embodiment

Refer to FIG. 28, which schematically illustrates a light generatingdevice in a light source system according to another embodiment of thepresent invention. In this embodiment, the light source system 2800includes a light generating device, a light division system, a firstspatial light modulator 2811 and a second spatial light modulator 2813.The light generating device includes excitation light sources 2801 and2802, a wavelength conversion device 2805, a first drive device 2806 anda first control device (not shown in the drawings). The light divisionsystem includes a filter plate 2814 and a reflecting mirror 2812.

Differences between this embodiment and the embodiment of FIG. 24include:

The light generating device of the light source system in FIG. 24generates a light sequence by sequentially turning on four lightsources, while the light generating device in this embodiment combinesusing a color wheel and sequentially turning on light sources togenerate a light sequence, as described below.

The wavelength conversion layer 2805 includes a first segment 2805A,second segment 2805B, third segment 2805C and a fourth segment 2805D,respectively carry first, second, third and fourth functional materials,to absorb the excitation light and respectively generate first, second,third and fourth lights. In this embodiment, the two excitation lightsources are both UV sources; the first and third segments carry a yellowwavelength conversion material, and the second and fourth segments carrya blue wavelength conversion material. Within one time interval, thefirst segment and third segment are respectively disposed on the outputpaths of the excitation lights of the two excitation light sources, andwithin another time interval, the second segment and fourth segment arerespectively disposed on the output paths of the excitation lights ofthe two excitation light sources.

The first drive device 2806 drives the wavelength conversion layer 2805,such that the light spots formed by the excitation lights on thewavelength conversion material layer 2805 fall on the wavelengthconversion material layer along predetermined paths. Meanwhile, thefirst control device controls the two excitation light sources, suchthat during at least a part of the time interval when the first segment2805A and the third segment 2805C are located on the path of theexcitation lights, the two excitation light sources are alternatinglyturned on, and during at least a part of the time interval when thesecond segment 2805B and the fourth segment 2805D are located on thepath of the excitation lights, the two excitation light sources aresimultaneously turned on.

One specific example is described with reference to FIG. 29, which is aplan view of an example of a wavelength conversion layer in the lightsource system of FIG. 28. In this embodiment, the wavelength conversionlayer 2805 has a disk shape, and the first segment 2805A and thirdsegment 2805C are located at 180 degree locations with respect to eachother, and the second segment 2805B and fourth segment 2805D are locatedat 180 degree locations with respect to each other. The first drivedevice 2806 is a motor that drives the wavelength conversion materiallayer to rotate. A line that connects the light spots formed by the twoexcitation lights on the wavelength conversion material layer 2805passes through the center of the disk, so that the two segments disposedat 180 degrees from each other will be simultaneously located on theoutput paths of the two excitation lights from the two excitation lightsource.

In this embodiment, the wavelength conversion material layer 2805 isreflective type, i.e., the paths of the excitation light and theconverted light are located on the same side of the wavelengthconversion material layer 2805. This may be implemented by providing areflecting mirror or reflecting film on the side of the wavelengthconversion material layer 2805 that faces away from the excitation lightsource. This is well-known technology and will not be described indetail here.

Two reflective cups 2803 and 2804 are provided on the output paths ofthe wavelength conversion material layer 2805, to respectively collectthe converted lights generated by the wavelength conversion materialafter absorbing the excitation lights from the excitation light sources2801 and 2802, referred to as the first converted light and secondconverted light, respectively. Each of the reflective cup has anaperture for transmitting the excitation light from the correspondingexcitation light sources. Each reflective cups separates itscorresponding excitation light and converted light using the differencein etendue of the two lights. It should be understood that when thewavelength conversion material layer is transmission type, i.e., whenthe light paths of the excitation light and converted light are on thetwo different sides of the wavelength conversion material layer, thereflective cups are not necessary. However, in the present embodiment,reflective type wavelength conversion materials and reflective cups areused, which can reduce loss of the light beam, whereby increasing thelight utilization efficiency.

The light division system divides each of the first light and thirdlight into two lights of different wavelength ranges and outputs themalong the first light path and the second light path, and also outputsthe second light and the fourth light along the first light path and thesecond light path. In this embodiment, the reflector 2812 is located onthe output path of the second converted light, and the first convertedlight and the reflected second converted light from the reflector 2812are incident on the two different sides of filter plate 2814. The filterplate 2814 reflects the green component of the yellow lights (i.e. thefirst light and the third light) and transmits the red component, andreflects blue light (i.e. the second light and the fourth light) to beoutput along the first light path and the second light path. DMD 2811modulates the light output along the first light path by the filterplate 2814, and DMD 2813 modulates the light output along the secondlight path by the filter plate 2814.

Preferably, the first converted light is collected by the reflective cup2803 and sent to light homogenizing device 2807 to be homogenized, andthen passes through the condenser lens 2810 to be output to the filterplate 2814. Similarly, the second converted light is collected by thereflective cup 2804 and sent to light homogenizing device 2808 to behomogenized, and then passes through the condenser lens 2809 to beoutput to the filter plate 2812. This way, the utilization efficiency ofthe first excitation light and second excitation light, reducing lightloss.

Refer to FIG. 30, which illustrates an operating sequence of the lightsource system of FIG. 28. Within a rotation period T of the wavelengthconversion material layer 2805, when the second segment 2805B and thefourth segment 2805D are respectively located on the light paths of thetwo excitation lights, the first control device controls the twoexcitation light sources to turn on, and the two DMDs both receive theblue light reflected from the filter plate 2814. When the first segment2805A and the third segment 2805C are respectively located on the lightpaths of the two excitation lights, during the first time interval t1,the first control device turns on the excitation light source 2802 andturns off the excitation light source 2801, so DMD 2813 receives thegreen light and DMD 2811 receives the red light; during the later timeintegral t2, the first control device turns on the excitation lightsource 2801 and turns off the excitation light source 2802, so DMD 2813receives the red light and DMD 2811 receives the green light.

Preferably, when the first segment 2805A and the third segment 2805C arerespectively located on the light paths of the two excitation lights,during a time interval t3, the first control device turns on bothexcitation light sources 2801 and 2802, so both DMD receives thecombined light of the red light and green light, i.e. a yellow light.This increases the brightness of the light source system.

In this embodiment, when the second segment 2805B and the fourth segment2805D are respectively located on the light paths of the two excitationlight sources, the lengths of the on times of the of the two excitationlight sources can be adjusted, so that the amounts of the blue lightsreceived by the two DMDs can be adjusted, which in turn adjusts thecolor of the output image of the light source system. Similarly, whenthe first segment 2805A and the third segment 2805C are respectivelylocated on the light paths of the two excitation light sources, thelengths of the on times of the of the two excitation light sources canbe adjusted, so that the amounts of the sequential red and green lightsreceived by the two DMDs can be adjusted.

In this embodiment, the two excitation light sources may alternativelybe blue light sources, and the second segment 2805B and the fourthsegments 2805D are each provided with a reflective region to reflect theblue lights. When the excitation light sources are laser sources,preferably, the second segment 2805B and the fourth segments 2805D areeach provided with a scattering material to eliminate coherence of theblue light.

In this embodiment, the first light, second light, third light andfourth light may also be different color lights, and the spectra of thefour lights and the transmission spectra of the filter plates used todivide the first light and third light may be determined based on theneed for the two DMDs,

Seventeenth Embodiment

Refer to FIG. 31, which schematically illustrates a light generatingdevice in a light source system according to another embodiment of thepresent invention. In this embodiment, the light source system includeslight generating device, light division system, a first spatial lightmodulator 3111 and a second spatial light modulator 3113. The lightgenerating device includes excitation light sources 3101 and 3102, awavelength conversion layer 3105, a first drive device 3106 and a firstcontrol device (not shown in the drawings). The light division systemincludes a filter plate 3109 and reflecting mirrors with apertures 3103and 3104.

Differences between this embodiment and the embodiment of FIG. 28include:

In the light source system of FIG. 28, a reflective cup is provided onthe output path of the wavelength conversion material layer 2805, sothat the light sequence generated by the light emitting device isreflect by the reflective cup and before entering the light divisionsystem. In this embodiment, instead of a reflective cup on the outputpath of the wavelength conversion material layer 3105, the lightdivision system is directly provided.

The filter plate 3109 of the light division system transmits the greencomponent of the yellow light and reflects the red component of theyellow light, and also transmits the second light and the fourth light(which are both blue lights in this embodiment). The excitation lightgenerated by the first excitation light source 3101 passes through theaperture of the reflecting mirror 3103 and the collimating lens 3108 tobe incident on the wavelength conversion layer 3105. The first convertedlight outputted from the wavelength conversion layer 3105 passes throughthe collimating lens 3108 and is reflected by reflecting mirror 3103 tofilter plate 3109. The excitation light generated by the secondexcitation light source 3102 passes through the aperture of thereflecting mirror 3104, filter plate 3109 and the collimating lens 3107to be incident on the wavelength conversion layer 3105. The secondconverted light outputted from the wavelength conversion layer 3105passes through the collimating lens 3107 and is incident on filter plate3109.

The operating sequence of the light source system of FIG. 31 is asfollows. Within the rotation period T of the wavelength conversion layer3105, when the second segment 2805B and the fourth segment 2805D arerespectively located on the light path of the two excitation lights, thefirst control device turns on the two excitation light source; DMD 3113receives the blue light transmitted through filter plate 3109, and DMD3111 receives the blue light transmitted through filter plate 3109 andreflected by reflecting mirror 3104. When the first segment 2805A andthe third segment 2805C are respectively located on the light path ofthe two excitation lights, during a first time interval t1, the firstcontrol device turns on excitation light source 3101 and turns offexcitation light source 3102; DMD 3113 receives a red light and DMD 3111receives a green light. During a later time interval t2, the firstcontrol device turns on the excitation light source 3102 and turns offexcitation light source 3101; DMD 3113 receives a green light and DMD3111 receives a red light.

For convenience of description, the above embodiments are illustrated byusing the examples where the first light and third light are yellowlights and the second light and fourth lights are blue lights. Inpractice, these four light beams can be other color lights, not limitedto the above description. Correspondingly, the transmission spectrum ofthe filter plates or filter devices of the light division system can bedesigned based on the requirements of the four lights.

In the above various embodiment, in the multi-segmented wavelengthconversion layers and multi-segmented filter devices, the arrangementsof the multiple segments on the wavelength conversion layers or filterdevices are not necessarily a circumferential distribution around therotation center; rather, the segments can be band shaped parallelregions, or other arrangements. Correspondingly, the drive device thatdrives the wavelength conversion device or filter device may be a devicethat drives a linear translation motion or other drive devices, suchthat the light spots formed by the light beams on the wavelengthconversion layer or the filter device fall on the wavelength conversiondevice or filter device along a linear path or other predeterminedpaths.

In the above embodiments, the output light of the two DMDs can beprojected to the same display region, to form an image, as shown in FIG.32, which schematically illustrates the structure of a light sourcesystem according to another embodiment of the present invention. Theoutput light of the two DMD can alternatively be projected to twodisplay regions to form two images, as shown in FIG. 33, whichschematically illustrates the structure of a light source systemaccording to another embodiment of the present invention.

The various embodiments of the present invention are describedprogressively, where each embodiment is described by emphasizing itsdifferences form some earlier embodiments. For portions of the variousembodiments that are similar to each other, references can be made toeach other.

The present invention also provides a projection system, including alight source system, which can have structures and functions asdescribed in the above embodiments. The projection system can employvarious display technologies, such as LCD (liquid crystal display)projection technology, DLP (digital light processor) technology, etc.Further, the above-described light source system can also be used forlighting, such as stage lighting.

The above-described embodiments illustrate the present invention but donot limit it to the particular embodiments. Equivalent structures andequivalent processes can be used which are based on the descriptionhere; the invention may also be applied to other related technicalfields. All of these are within the scope of the present invention.

What is claimed is:
 1. A light source system, comprising: a lightgenerating device which includes a first light emitting devicegenerating a yellow light, a second light emitting device generating ablue light and a first control device; a light division system whichdivides the yellow light into a light in a first wavelength range and alight in a second wavelength range and outputs them along a first lightpath and a second light path, respectively, and which outputs the bluelight along the first light path; a first spatial light modulator, whichmodulates the lights outputted along the first light path of the lightdivision system; and a second spatial light modulator, which modulatesthe lights outputted along the second light path of the light divisionsystem; and wherein the first control device alternatingly turns on thefirst light emitting device and the second light emitting device duringat least some time intervals, and simultaneously turns on the firstlight emitting device and the second light emitting device during atleast some other time intervals, wherein the light in the firstwavelength range in the first light path and the light in the secondwavelength range in the second light path are always on and off at thesame time.
 2. The light source system of claim 1, wherein the firstlight emitting device is a yellow LED and the second light emittingdevice is a blue LED.
 3. The light source system of claim 1, wherein thelight in a first wavelength range is green light, and the first spatiallight modulator modulates a combined light which simultaneously containsthe blue light and green light during at least some time intervals. 4.The light source system of claim 1, wherein the light in a firstwavelength range is red light, and the first spatial light modulatormodulates a combined light which simultaneously contains the blue lightand red light during at least some time intervals.
 5. A projectionsystem comprising the light source system of claim
 1. 6. The lightsource system of claim 1, wherein within each time period of a series oftime periods, the first control device turns on the first light emittingdevice and turns off the second light emitting device during a firsttime interval, turns off the first light emitting device and turns onthe second light emitting device during a second time interval, andturns on both the first light emitting device and the second lightemitting device during a third time interval, the first, second andthird time intervals being non-overlapping.